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The Universe

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Some Essential Definitions

  • Astronomical Units:- The unit of length which is roughly the distance of the sun between the earth is called Astronomical unit.
  • 1 AU=150 Million Kilometers or 93 million miles

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  • Light Year:-The distance covered by the light in a year is called one light year.
  • Parsec:- The unit of length used to measure the astronomical object ,basically outside the solar system.

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Solar system

  • A solar system is the group of the sun,eight planets and their moons that orbit round the sun,together with smaller bodies in the form of asteroids ,meteoroids and comets.
  • Eight planets are:-
  • Mercury
  • Venus
  • Earth
  • Mars
  • Jupiter
  • Saturn
  • Uranus
  • Neptune

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Stars

  • Evolution of stars:- The description of the way that changes the time is called Evolution of stars.
  • The time span between the birth and the death of the stars is called their lifetime.
  • Nebula is called nursery of star why?
  • It is because stars are formed where nebula is present.

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EVOLUTION OF STARS

Protostar

Main sequence like star

Red Giant and super red giant

White dwarf and black dwarf

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Neutron star and

Black Hole

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Some Nationals and Internationals Research Organizations

  • Nepal Academy of Science and Technology(NAST)
  • International Astronomical Union (IAU)
  • National Aeronautics and Space Administration(NASA)

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